78 lines
2.7 KiB
C#
78 lines
2.7 KiB
C#
//-----------------------------------------------------------------------
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// -----------------------------------------------------------------------
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// file="Sqrt.cs"
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// Project: StgSharp
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// AuthorGroup: Nitload Space
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// Copyright (c) Nitload Space. All rights reserved.
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//
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// Permission is hereby granted, free of charge, to any person
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// obtaining a copy of this software and associated documentation
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// files (the “Software”), to deal in the Software without restriction,
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// including without limitation the rights to use, copy, modify, merge,
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// publish, distribute, sublicense, and/or sell copies of the Software,
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// and to permit persons to whom the Software is furnished to do so,
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// subject to the following conditions:
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//
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// The above copyright notice and
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// this permission notice shall be included in all copies
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// or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED “AS IS”,
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// WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
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// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
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// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
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// ARISING FROM, OUT OF OR IN CONNECTION WITH
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// THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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//
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// -----------------------------------------------------------------------
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// -----------------------------------------------------------------------
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using System;
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using System.Runtime.CompilerServices;
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namespace StgSharp.Mathematics
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{
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public static partial class Scaler
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{
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public static unsafe float SeedSqrt(float x)
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{
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ArgumentOutOfRangeException.ThrowIfNegative(x);
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if (x <= 1e-12) {
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return 0;
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}
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uint a = *(uint*)&x;
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uint f = a;
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f >>= 23;
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f /= 2;
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f += 64;
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a -= 0b_0011_1111_0000_0000_0000_0000_0000_0000;
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uint e = a << 8;
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e >>= 8;
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e *= 0b_1101_0001;
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e >>= 24;
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e += 0b_0000_0000_0001_0000_1010_1000_1110_0010;
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f <<= 23;
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e += f;
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float result = *(float*)&e;
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result = (result + (x / result)) / 2;
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return (result + (x / result)) / 2;
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}
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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public static float Sqrt(float x)
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{
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return MathF.Sqrt(x);
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/**/
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}
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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public static double Sqrt(double x)
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{
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return System.Math.Sqrt(x);
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}
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}
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}
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